When Norman Mail Pigeon arrives with a mysterious blue envelope addressed to Eric Seagull, Rock-Face Nest at St Mary's Bay, in sunny South Devon, the herring gull finds himself in all sorts of trouble. Leaving his tiny best friend and housemate Herbie the white mouse behind, he begins his journey to save his French cousin Percy. He is caught in a thunderstorm, tumbles from the sky, and has a brief meeting with Harry the Whale. Magic bubbles appear from nowhere, and a Mermaid Queen casts a dodgy magic spell, which changes Eric into a swordfish-gull. Whatever will happen next?